Source code for octavia.amphorae.backends.utils.network_namespace

# Copyright 2020 Red Hat, Inc. All rights reserved.
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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import ctypes
import os


[docs] class NetworkNamespace(object): """A network namespace context manager. Runs wrapped code inside the specified network namespace. :param netns: The network namespace name to enter. """ # from linux/sched.h - We want to enter a network namespace CLONE_NEWNET = 0x40000000 @staticmethod def _error_handler(result, func, arguments): if result == -1: errno = ctypes.get_errno() raise OSError(errno, os.strerror(errno)) def __init__(self, netns): self.current_netns = '/proc/{pid}/ns/net'.format(pid=os.getpid()) self.target_netns = '/var/run/netns/{netns}'.format(netns=netns) # reference: man setns(2) self.set_netns = ctypes.CDLL('libc.so.6', use_errno=True).setns self.set_netns.errcheck = self._error_handler def __enter__(self): # Save the current network namespace self.current_netns_fd = open(self.current_netns, encoding='utf-8') with open(self.target_netns, encoding='utf-8') as fd: self.set_netns(fd.fileno(), self.CLONE_NEWNET) def __exit__(self, *args): # Return to the previous network namespace self.set_netns(self.current_netns_fd.fileno(), self.CLONE_NEWNET) self.current_netns_fd.close()